Back button now returns to start screen. Also fix #356

app/src/main/java/eu/kanade/tachiyomi/ui/main/MainActivity.kt

@@ -3,6 +3,7 @@ package eu.kanade.tachiyomi.ui.main
 import android.content.Intent
 import android.os.Bundle
 import android.support.v4.app.Fragment
+import android.support.v4.app.TaskStackBuilder
 import android.support.v4.view.GravityCompat
 import android.view.MenuItem
 import eu.kanade.tachiyomi.R
@@ -23,6 +24,15 @@ class MainActivity : BaseActivity() {
 
     val preferences: PreferencesHelper by injectLazy()
 
+    private val startScreenId by lazy {
+        when (preferences.startScreen()) {
+            1 -> R.id.nav_drawer_library
+            2 -> R.id.nav_drawer_recently_read
+            3 -> R.id.nav_drawer_recent_updates
+            else -> R.id.nav_drawer_library
+        }
+    }
+
     override fun onCreate(savedState: Bundle?) {
         setAppTheme()
         super.onCreate(savedState)
@@ -45,28 +55,28 @@ class MainActivity : BaseActivity() {
             // Make information view invisible
             empty_view.hide()
 
-            when (item.itemId) {
-                R.id.nav_drawer_library -> setFragment(LibraryFragment.newInstance())
-                R.id.nav_drawer_recent_updates -> setFragment(RecentChaptersFragment.newInstance())
-                R.id.nav_drawer_recent_manga -> setFragment(RecentlyReadFragment.newInstance())
-                R.id.nav_drawer_catalogues -> setFragment(CatalogueFragment.newInstance())
-                R.id.nav_drawer_downloads -> setFragment(DownloadFragment.newInstance())
-                R.id.nav_drawer_settings -> startActivity(Intent(this, SettingsActivity::class.java))
-                R.id.nav_drawer_backup -> setFragment(BackupFragment.newInstance())
+            val id = item.itemId
+            when (id) {
+                R.id.nav_drawer_library -> setFragment(LibraryFragment.newInstance(), id)
+                R.id.nav_drawer_recently_read -> setFragment(RecentlyReadFragment.newInstance(), id)
+                R.id.nav_drawer_recent_updates -> setFragment(RecentChaptersFragment.newInstance(), id)
+                R.id.nav_drawer_catalogues -> setFragment(CatalogueFragment.newInstance(), id)
+                R.id.nav_drawer_downloads -> setFragment(DownloadFragment.newInstance(), id)
+                R.id.nav_drawer_settings -> {
+                    val intent = Intent(this, SettingsActivity::class.java)
+                    startActivityForResult(intent, REQUEST_OPEN_SETTINGS)
+                }
+                R.id.nav_drawer_backup -> setFragment(BackupFragment.newInstance(), id)
             }
             drawer.closeDrawer(GravityCompat.START)
             true
         }
 
         if (savedState == null) {
+            // Set start screen
+            setSelectedDrawerItem(startScreenId)
 
-            when (preferences.startScreen()) {
-                1 -> setFragment(LibraryFragment.newInstance())
-                2 -> setFragment(RecentlyReadFragment.newInstance())
-                3 -> setFragment(RecentChaptersFragment.newInstance())
-                else -> setFragment(LibraryFragment.newInstance())
-            }
-
+            // Show changelog if needed
             ChangelogDialogFragment.show(preferences, supportFragmentManager)
         }
     }
@@ -80,23 +90,45 @@ class MainActivity : BaseActivity() {
     }
 
     override fun onBackPressed() {
-        supportFragmentManager.findFragmentById(R.id.frame_container)?.let {
-            if (it !is LibraryFragment) {
-                nav_view.setCheckedItem(R.id.nav_drawer_library)
-                nav_view.menu.performIdentifierAction(R.id.nav_drawer_library, 0)
-            } else {
-                super.onBackPressed()
+        val fragment = supportFragmentManager.findFragmentById(R.id.frame_container)
+        if (fragment != null && fragment.tag.toInt() != startScreenId) {
+            setSelectedDrawerItem(startScreenId)
+        } else {
+            super.onBackPressed()
+        }
+    }
+
+    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
+        if (requestCode == REQUEST_OPEN_SETTINGS && resultCode != 0) {
+            if (resultCode and SettingsActivity.FLAG_DATABASE_CLEARED != 0) {
+                // If database is cleared avoid undefined behavior by recreating the stack.
+                TaskStackBuilder.create(this)
+                        .addNextIntent(Intent(this, MainActivity::class.java))
+                        .startActivities()
+            } else if (resultCode and SettingsActivity.FLAG_THEME_CHANGED != 0) {
+                recreate()
             }
-        } ?: super.onBackPressed()
+        }
     }
 
-    fun setFragment(fragment: Fragment) {
+    private fun setSelectedDrawerItem(itemId: Int, triggerAction: Boolean = true) {
+        nav_view.setCheckedItem(itemId)
+        if (triggerAction) {
+            nav_view.menu.performIdentifierAction(itemId, 0)
+        }
+    }
+
+    private fun setFragment(fragment: Fragment, itemId: Int) {
         supportFragmentManager.beginTransaction()
-                .replace(R.id.frame_container, fragment)
+                .replace(R.id.frame_container, fragment, "$itemId")
                 .commit()
     }
 
     fun updateEmptyView(show: Boolean, textResource: Int, drawable: Int) {
         if (show) empty_view.show(drawable, textResource) else empty_view.hide()
     }
+
+    companion object {
+        private const val REQUEST_OPEN_SETTINGS = 200
+    }
 }

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsActivity.kt

@@ -16,6 +16,15 @@ class SettingsActivity : BaseActivity(),
 
     private lateinit var replaceFragmentStrategy: ReplaceFragment
 
+    /**
+     * Flags to send to the parent activity for reacting to preference changes.
+     */
+    var parentFlags = 0
+        set(value) {
+            field = field or value
+            setResult(field)
+        }
+
     override fun onCreate(savedState: Bundle?) {
         setAppTheme()
         super.onCreate(savedState)
@@ -29,10 +38,16 @@ class SettingsActivity : BaseActivity(),
             supportFragmentManager.beginTransaction()
                 .add(R.id.settings_content, SettingsFragment.newInstance(null), "Settings")
                 .commit()
+        } else {
+            parentFlags = savedState.getInt(SettingsActivity::parentFlags.name)
         }
 
         setupToolbar(toolbar, backNavigation = false)
+    }
 
+    override fun onSaveInstanceState(outState: Bundle) {
+        outState.putInt(SettingsActivity::parentFlags.name, parentFlags)
+        super.onSaveInstanceState(outState)
     }
 
     override fun onOptionsItemSelected(item: MenuItem): Boolean {
@@ -60,4 +75,9 @@ class SettingsActivity : BaseActivity(),
         return true
     }
 
+    companion object {
+        const val FLAG_THEME_CHANGED = 0x1
+        const val FLAG_DATABASE_CLEARED = 0x2
+    }
+
 }

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsAdvancedFragment.kt

@@ -97,6 +97,7 @@ class SettingsAdvancedFragment : SettingsFragment() {
                 .positiveText(android.R.string.yes)
                 .negativeText(android.R.string.no)
                 .onPositive { dialog, which ->
+                    (activity as SettingsActivity).parentFlags = SettingsActivity.FLAG_DATABASE_CLEARED
                     db.deleteMangasNotInLibrary().executeAsBlocking()
                     activity.toast(R.string.clear_database_completed)
                 }

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsGeneralFragment.kt

@@ -1,8 +1,6 @@
 package eu.kanade.tachiyomi.ui.setting
 
-import android.content.Intent
 import android.os.Bundle
-import android.support.v4.app.TaskStackBuilder
 import android.support.v7.preference.Preference
 import android.support.v7.preference.PreferenceFragmentCompat
 import android.support.v7.preference.XpPreferenceFragment
@@ -67,16 +65,14 @@ class SettingsGeneralFragment : SettingsFragment(),
         }
 
         themePreference.setOnPreferenceChangeListener { preference, newValue ->
-            // Rebuild activity's to apply themes.
-            TaskStackBuilder.create(context)
-                    .addNextIntentWithParentStack(Intent(activity.intent))
-                    .startActivities()
+            (activity as SettingsActivity).parentFlags = SettingsActivity.FLAG_THEME_CHANGED
+            activity.recreate()
             true
         }
     }
 
     override fun onPreferenceDisplayDialog(p0: PreferenceFragmentCompat?, p: Preference): Boolean {
-        if (p.key == getString(R.string.pref_library_columns_dialog_key)) {
+        if (p === columnsPreference) {
             val fragment = LibraryColumnsDialog.newInstance(p)
             fragment.setTargetFragment(this, 0)
             fragment.show(fragmentManager, null)

app/src/main/res/menu/menu_navigation.xml

@@ -8,7 +8,7 @@
             android:icon="@drawable/ic_book_black_24dp"
             android:title="@string/label_library" />
         <item
-            android:id="@+id/nav_drawer_recent_manga"
+            android:id="@+id/nav_drawer_recently_read"
             android:icon="@drawable/ic_glasses_black_24dp"
             android:title="@string/label_recent_manga"/>
         <item